A crawler-type or tracked vehicle is normally supported and propelled by an undercarriage assembly having an endless track entrained about a drive roller or sprocket, a front idler roller, a rear idler roller, and a series of track rollers. The drive roller or sprocket is driven by an engine of the work vehicle which, in turn, causes the endless track to be advanced around each of the front and rear idler rollers as well as the track rollers to advance the work vehicle.
For an endless track to function properly, it must be properly tensioned around the several rollers, and the several rollers must be properly maintained to ensure they roll with the least amount of friction while supporting the weight of the vehicle. Tracked vehicles are normally considerably heavy. As a result, the rollers are prone to generate substantial frictional heat as they are made to roll as the tracked vehicle advances. Excessive frictional heat in the rollers can lead to roller failure and expensive and time-consuming repair costs. Limiting frictional heat in rollers is accomplished with a lubricating oil, which is applied to and maintained by reservoirs formed in the rollers. The lubricating oil must be periodically replenished, and periodically replaced to ensure the oil functions properly, namely, that it reduces roller friction and draws and dissipates heat away from the rollers. Contaminated or dirty oil and reduced oil levels impede the ability of the oil to reduce friction and dissipate heat. Accordingly, proper oil maintenance in rollers is essential for proper operation of the tracked vehicle and to limit unnecessary and time-consuming roller repairs.